Question

How is compound A related to compounds B–E? Choose from enantiomers, diastereomers, constitutional isomers, or identical molecules.

Short answer

Compound A and Compound B are diastereomers.

Compound A and Compound C are identical molecules.

Compound A and Compound D are enantiomers.

Compound A and Compound E are constitutional isomers.

Step-by-step solution

Enantiomers and Diastereomers

The R, S configuration is different for enantiomers, but one stereocenter will have a similar configuration in the diastereomer.An example of an enantiomer is lactic acid, and that of a diastereomer is tartaric acid.

Constitutional isomers

An isomer pair that possesses a matching molecular formula but has different connectivity are constitutional isomers.An example of a constitutional isomer is butane and isobutane.

Relation of compound A with compounds B, C, D, and E

Relation of compound A with compound B

Compounds A (trans, R) and B (cis, R) have different geometry around the double bond and the same configuration around the stereogenic center. Hence, compounds A and B are diastereomers.

Relation of compound A with compound C

Compounds A(trans, R) and C(trans, R) have the same geometry around the double bond and the same configuration around the stereogenic center. Hence,compounds A and C are identical.

Relation of compound A with compound D

Compounds A (trans, R) and D (trans, S) have the same geometry around the double bond and different configurations around the stereogenic center. Hence,compounds A and D are enantiomers.

Relation of compound A with compound E

Compounds A (trans, R) and E have the same molecular formula but varying connectivity. Hence,compounds A and E are constitutional isomers.